Inductively heated shoemaking apparatus



Sept. 9, 1952 w. s. ROBSON 2,610,287

INDUCTIVELY HEATED SHOEMAKING APPARATUS Filed Feb. 26, 1949 2SHEETSSHEET 1 In van zar wzmam Jelwyn Robson his flzffor'neg Sept. 9,1952 w. s. RoBsoN 2,610,287

INDUCTIVELY HEATED SHOEMAKING APPARATUS Filed Feb. 26, 1949 2SHEETSSHEET 2 I In van far William Selwg n P0278012 v5g: hjiirnqyPatented Sept. 9, 1952 INDUCTIVELY HEATED SHOEMAKING APPARATUS.

William. Selwyn. Robson, Leicest'er England, as-

signor to United Shoe Machinery Corporation, Flemington, N. J acorporation of New Jersey Application February 26, 1949, Serial No.78,534 In Great Britain March .4, 1948 6' Claims. 1

This. invention relates. .to improvementsjin apparatus for themanufacture of shoes and more particularly to apparatus for. useinlasting shoes especially where the shoe. upper is. permanently secured.to the insole. by means of. an adhesive.

In. the. manufacture of certain shoes in which the. marginal portion of.an. upper,, around the toe. of a. shoe, is tobe secured.inJlastedrelat-ion to a. shoe bottom member (e. e. an, insole)v bymeans, of an adhesive, the upper on. a last may baconformed tothe shapeofthe last by the employment. of a lasting machine of the so-calledbed-lasting. machine type. (for example, the typedisclosed inUnitedStatesLetters PatentNo. 2,097,567., granted November 2,1937 uponan application. of F. B. Keall) which operates. to wipe the-marginalportion of the. upper. aroundthe toe of the. shoe over. the edge of.an..insole-. on. the last-bottom, inwardly of the edge. of the insole.Thereafter this portion .is, secured. in place by means of adhesivepreviously applied between the portion: and the margin of theinsole.

In. some. cases ithas. been proposedto. hold the marginal portion ofthe. upper, at the toe, in lasted. relation to the. insole, while. theadhesive issetting, by means of a toe plate'or other temporary holding.means which is secured to the shoe. bottom. and, remains, on the shoewhen the latter. is removed. from. the. lasting machine. After the.adhesive. has set, the temporary up.- per. holding means is removed fromthe shoe.

In order to speedup thesetting of the adhesive and. thereby render the.use of such temporary upper holding meansv unnecessary, ltihas beenproposed that. a heated device, correspondingin outline tov the toe of ashoe, be placed by the operator. on the wiped over margin of the upper(the wipers. having been momentarily lifted away from .or. backed offfrom that margin to enable the device to be placed in position thereon).Pressure is then applied to the device. by meansof the wipers, and aftera few seconds (the actual length of time. depending upon the temperatureof the device. and the pressure applied) the. adhesive will? have.become sufliciently set" to permit the shoe to be removed from thelastin machine and subjected without .undue delay to the nextmanufacturing operation to be performed thereon.

A device which has been used for this purpose takes. the form of a smallhand tool comprising a U-shaped plate-like member attached to a handle,the member being designed to be heated by placing it in a gas flamebetween lasting operations on consecutive shoes. The use of gas heated,tools has the disadvantage: of the production of undesirable fumes; andthe naked flame constitutes an appreciable fire risk, especially whenadhesive producing inflammable solvent vapors are employed. It has alsobeen pro-- posed to use portable electrically heated tools for 2. thispurpose, but such use has met little suecessin practice hitherto due tothe fact that the electric elements do. not stand up to prolonged useunder shoe factory conditions wherein the tools are subjected to severejolts, tending quickly to disrupt the elements. Another disadvantage ofsuch a tool is the necessity for the use of trail,- ing; supply leads.which tend. to. catch on pro.- iecting portions. of the machine and.generally get in. the operators way.

It is an object of the invention to provide an improved organization ofapparatus. for accelcrating the setting of the toe lasting adhesivewhich does not suiier. from. the. above-mentioned disadvantages.

Another object. of the invention is to provide an improved transformerapparatus for inducing heating. currents, for example, in. portabletools comprising a closed conductive loop adapted to form the secondaryof. a transformer, whereby such tools; may be. conveniently andefficiently heated.

Further objects. and advantages of the, inventionv will be apparent andthe. invention itself willbe. best. understood withreference-to thefollowing specification and the. accompanying drawings in which Fig, 1is, an. angular view of an organization comprising a transformerapparatus and aportable. hand tool adapted. to be inductively heated forsubsequent. use in. accelerating the setting of toe lasting adhesive ina bed-lasting, machine, said tool being shown positioned for. heating insaid transformer apparatus;

Fig. 2. is an angular view. of the portable. tool shown in Fig. 1;

Fig. 3. is a side elevation of the transformer apparatusshown in Fig. 1;and

Fig; 4' is a diagram of the electric circuit in.- volved in. thetransformer apparatus shown. in Fig. 1.

The hand tool shown in Fig. 2 is constructed tohave its heated portionform part of a closed conductive loop which is adapted to link the coreof a transformer and form the secondary Wind'- ing thereof, whereby saidportion is heated by hysteresis and the high current'induced. in theloop. The tool comprises a U-shaped plate-like member ll made of steeland conformed to the toe portion of a shoe bottom. Joining the ends ofthis member and connected thereto in a manner providing a minimum ofresistance, asby welding, is a bridge member 13 of ametal of relativelygreater conductivity than the plate-like member, for example; beingconveniently made of copper. A short metal rod I-I- extends up-'wardlyand rearwardly away from the bridge member I3 to which it isattached, and to this rod is secured'a wooden handle Hi.

The tool shown in Fig. 2 is adapted for use particularly with a machineof the type disclosed Because of the greater conductivity of the Theprimary coil 30 is adapted for connection by leads 6!) and 62 to asource of alternating current having a potential sufficient to attractthe armature 36 into closing relation with the core 22. When a tool isnot being heated, a resistance 65 is interposed between lead 60 and thecoil. This resistance is sufiicient to reduce the potential of thealternating current supplied to bridge member and the conversely greaterresistivity of the plate-like member ll, an induced current flowingthrough the closed loop comprising theconnected members II and l3 willproduce a greater heating effect in the plate-like member I l than inthe bridge member [3. Accordingly, that portion of the tool which is tobe applied to the shoe bottom will be heated to a greater extent thanthat portion of the tool carrying the handle, resulting in a greaterdegree of efiiciency than if the conductive loop were of uniformconductivity. At the same time this arrangement tends to keep the handlerelatively cool.

Apparatus for inducing a heating current in the tool is shown in Figs. 1and 3. These figures illustrate certain features of the invention,

including the means by which the closed loop of the tool may be linkedwith a flux core to form the secondary of a transformer and yet bereadily removable from said core for application to a shoe.

The apparatus comprises a base plate 20 upon which a U-shapedtransformer core 22 is supported on brackets 24 and 26 with the limbs ofthe core vertically disposed, one limb near the front and one rearwardlythereof. The crossmember 23 of the core, corresponding to the base ofthe U, carries a winding 32 which forms the primary coil of thetransformer apparatus. Attached to the two sides of the rear limb of thecore and extending rearwardly and upwardly therefromare plates 32between which an armature assembly 33 is pivoted on a pivot pin 34. Thearmature assembly comprises an armature 36 (effectively comprising asection of transformer core) supported between two parallel metal strips38 by bolts 4,!) (Fig. 1), the strips 38 extending rearwardly beyond thearmature where they are journaled on the pivot pin 34. Accordinglythearmature is movable into bridging relation with the ends of core 22 toprovide a magnetic circuit of low reluctance. In another aspect, thecore and armature together may be regarded as a substantially.rectangular transformer core having a portion movable into spacedrelation with the remaining portion.

Normally, that is, while the apparatus is in use, except during theheating cycle, the armature is maintained in spaced relation with theremainder of the core by being urged upward and out of engagement withthe upper faces of the limbs of core 22 by a spring 42 extending betweena transverse pin 44 in the armature assembly 33 and a transverse pin 46between the plates 32. The spring 42 surrounds a rod 48 which extendsradially from the pin 44, passing through a bore extending diametricallythrough the pin 46. The upper end of the spring engages a collar 50secured to the rod while the lower end of the spring engages a collar 52slidable onrod 48. A stop collar 54 is secured to the rod 48 at itslower end.

the coil to a value at which the attraction between the ends ofcore 22and the armature 36 is insufficient to overcome the force of the springDuring the heating cycle, the resistance 64 is shunted by a mercuryswitch 66 extending forwardly and rearwardly of the apparatus andpivotally mounted adjacent to its rear end on a transverse pin 68carried by side plate 12 forming the bracket which supports the frontend of the core 22. A cross-piece 74 extends transversely between upperend portions of the side plates 12, and through a hole in thiscross-piece a rod 76 extends downwardly to support the forward end ofthe mercury switch, the rod in turn being suported by a spring 18extending between a collar 80 and the cross-piece M. The mercury switchis normally held in the tilted position shown in Fig. 3 so that it doesnot shunt out the resistance 84, but when a toll such as thatillustrated in Fig. 2 is positioned in linking relation on the forwardlimb of core 22 through the space provided by the open armature, theweight of the tool resting on collar 80 depresses rod 16 to pivot themercury switch to a more horizontal position in which it shunts out theresistance 64.

In this position, the energy supplied to the primary coil is sufficientto cause the armature 36 to move into engagement with the upper facesofthe limbs of core 22. The armature remains in this closing relation withthe core until the tool is lifted, whereupon spring 18 returns themercury switch 66 to a tilted position, efiectively inserting theresistance 64 in series relation with the supply circuit. Thereupon thecurrent in coil 3%] becomes insufficient to hold the armature in suchclosing relation. The small current which flows through the coil underthese circumstances advantageously overcomes any remanent magnetism inthe core which might tend to keep the armature attracted thereto. Thissmall current insures that at some instant in the current cycle thismagnetism is reduced to zero, any subsequent increase in the magneticfield during the flow of this small current being insufficient to causethe armature to be held in its closed position.

In the illustrative apparatus (Fig. l) the lower portion of the core,the lower part of the primary coil, the resistance and the switch areconveniently enclosed in a metal case having ventilating holes 92 in itswalls, while the upper part of the coil is protected by means of. anasbestos bridge piece 94 extending between the limbs of the core, whichbridge piece protects the windings of the coil from contact with theheating tool and from heat radiated therefrom.

In operation the operator finds the heating apparatus with its armaturespaced from the core. Through the gap thereby provided, the tool, shownin Fig. 2, is positioned in linking relation with the forward limb ofthe transformer core. In this position, the tool rests as shown in Figl, with its weight primarily supported upon the collar 80, causing themercury switch to be closed and the armature to be attracted to aposition in closing relation with the core, in which position a, pathfor the magnetic flux is provided which is substantially free from airgaps. Accordingly the tool is physically linked with the core and isinductively coupled to a maximum flux, the leakage flux being reduced toa minimum by the closing or" the core.

When the tool is heated, the operator may then grasp it by its handle,lifting it away from the collar 89 and allowing the mercury switch to betilted to the off-position, whereupon the armature is released to bemoved to a spaced relation with the core under the urging of the spring42 so that the tool may be conveniently removed.

Although the invention has been described in connection with theillustrated apparatus, numerous variations Within the scope of theinvention will occur to those skilled in the art and accordingly theclaims are to be given a broad interpretation consistent therewith.

Having described my invention, what I claim as new and desire to secureby Letters Patent of the United States is:

1. In apparatus of the class described, a portable heating toolcomprising a closed conductive loop and a handle, a transformer corehaving a fixed portion and a portion movable with respect to said fixedportion to provide space for admitting said tool into linking relationwith said core, a coil on the fixed portion of said core, a spring forurging said movable portion into spaced relation with said fixedportion, and a switch operated by the positioning of the tool in apredetermined position in linked relation with said core for connectingsaid coil to a supply of alternating current sufficient to close saidmovable portion by magnetic attraction.

2. Apparatus for inducing heating current in a closed loop heating toolcomprising a core forming an incomplete loop having spaced ends, aprimary coil on said core, an armature pivoted for movement into and outof engagement with the ends of said core to bridge the gap therebetween,a spring for yieldingly urging said armature out of contact with thecore, means for connecting said coil to a source of alternating currentthrough a resistance sufficient to limit the current to an amountinsufiicient to cause said armature to be attracted to said core againstthe force of the spring, and a switch arranged to be operated by theweight of such a tool for shunting out said resistance when the tool isresting in linked relation with said apparatus.

3. In apparatus of the class described, a portable hand tool in the formof a closed conductive loop having a handle attached thereto, atransformer core forming an incomplete loop having spaced ends andcarrying a primary coil, an armature comprising a transformer coresection movable into and out of bridging relation with said ends, aspring for yieldingly urging said armature out of said bridgingrelation, and means for connecting the coil to a source of alternatingcurrent comprising a switch adjacent to said core and adapted to be heldclosed by the weight of said tool while the tool is disposed in linkedrelation with the core during the heating cycle to supply alternatingcurrent to said coil sufiicient to attract said armature into saidbridging relation, said switch being actuated by resilient means, uponthe lifting of said tool, to effectively insert in circuit a, seriesresistance sufficient to reduce the supply of current to the coil to anamount sufficient to overcome any remanent magnetism but insufficient tohold said armature in closing relation with said core.

4. Inductive heating apparatus comprising a transformer core, a portionof said core being movable into spaced relation from the remainingportion of said core to provide a gap by which a closed loop tool may belinked with said core, means for maintaining said movable portionnormally in spaced relation with said remaining portion, a primary coilon a portion of said core, and means responsive to the movement of saidtool into a predetermined heating position for connecting said coil to asource of alternating current sufficient to attract said movable portioninto a position in closing relation with said remaining portion, saidconnecting means being also responsive to movement of said tool awayfrom said linked, heating position, preliminary to unlinking it withsaid loop, for reducing the supply of current to the coil before themovable portion of the core is moved into spaced relation with theremaining portion.

5. Inductive heating apparatus comprising a transformer core having anopening therein, an armature movable to close said opening, means formaintaining said armature normally in an open position, a primary coilon said core, means for supplying said coil with alternating currentcomprising a resistance in series relation with said coil and sufiicientto reduce the potential of the alternating current supplied to said coilto an amount insufiicient to hold said armature in its closing position,and a switch actuated by the positioning of a tool in linked relationwith the magnetic circuit of said heating apparatus for shunting outsaid resistance.

6. Inductive heating apparatus comprising a transformer core, a portionof said core being movable into spaced relation from the remainingportion of said core to provide a gap by which a closed loop may belinked with said core, a primary coil on a portion of said core, meansadapted to be actuated by the weight of a closedloop-tool, disposed in apredetermined position in linked relation with said core, forcontrolling the supply of alternating current to said coil, said supplyof power being sufiicient to close said core when applied, and meansyielding upon such application for maintaining said core portionnormally in said spaced relation.

WILLIAM SELW YN ROBSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

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